In many fields such as chemical research, for example, it is desirable to be able to dispense a metered amount of fluid in exact amounts. To this end there have been employed burettes, pipettes and the like and additionally there have been developed certain commercially available liquid dispensers having measuring means for rapidly dispensing rather precise amounts of liquid. Various devices of this type have been patented such as, for example, the pipette of U.S. Pat. No. 2,798,647, the measuring colorant dispenser of U.S. Pat. No. 3,118,568, and the liquid dispensing devices of U.S. Pat. Nos. 3,143,252, 3,211,335 and 3,452,901.
In addition to the provision of a dispenser for liquid which is capable of accurately metering the amount of liquid dispensed, it is desirable for the dispensing means or device to be relatively simple, rugged and maintenance-free, and to be easily purged of air and to maximize reproducibility of results. Various improvements along these lines are incorporated in the devices of the above-noted patents.
The present invention provides a further improvement in liquid dispensers over the improvements of the prior art including those of the above-noted patents. In particular, the present invention provides for a liquid dispenser adapted to fit upon a liquid container and provide a substantially flat top for the container when the dispenser is not in use. This is highly advantageous in providing maximum protection for the parts of the dispenser and also for providing the capability of stacking liquid containers having the liquid dispenser hereof attached thereto. As an example of the advantages of a flat upper profile afforded by the present invention is the intermittent dispensing of liquids requiring a particular environment for storage such as, for example, refrigeration. Normally, only limited storage space is available for liquid containers requiring a particular environment and thus it is highly advantageous to be able to stack these containers and the present invention provides this capability. A further advantage is found in shipping of such containers which occupy less room and are less susceptible to breakage. It is also noted that the low profile enhances the stability of the device.